From: Soeren Apel <redacted>
Date: Wed, 17 May 2017 06:31:07 +0000 (+0200)
Subject: DecodeSignal: Rework samplerate handling
X-Git-Url: https://sigrok.org/gitweb/?p=pulseview.git;a=commitdiff_plain;h=a3ebd5561086f4fef6570b3ab5be0a5592724731

DecodeSignal: Rework samplerate handling

Before, running an acquisition, then changing the
samplerate and then running the acquisition again
would result in the wrong (i.e. previous) samplerate
to be used for SRD. This patch fixes this.
---

diff --git a/pv/data/decodesignal.cpp b/pv/data/decodesignal.cpp
index a7bcee59..339c85dd 100644
--- a/pv/data/decodesignal.cpp
+++ b/pv/data/decodesignal.cpp
@@ -221,13 +221,6 @@ void DecodeSignal::begin_decode()
 		}
 	}
 
-	// TODO Currently we assume all channels have the same sample rate
-	auto any_channel = find_if(channels_.begin(), channels_.end(),
-		[](data::DecodeChannel ch) { return ch.assigned_signal; });
-	shared_ptr<LogicSegment> first_segment =
-			any_channel->assigned_signal->logic_data()->logic_segments().front();
-	samplerate_ = first_segment->samplerate();
-
 	// Free the logic data and its segment(s) if it needs to be updated
 	if (logic_mux_data_invalid_)
 		logic_mux_data_.reset();
@@ -240,12 +233,6 @@ void DecodeSignal::begin_decode()
 		logic_mux_data_->push_segment(segment_);
 	}
 
-	// Update the samplerate and start time
-	start_time_ = segment_->start_time();
-	samplerate_ = segment_->samplerate();
-	if (samplerate_ == 0.0)
-		samplerate_ = 1.0;
-
 	// Make sure the logic output data is complete and up-to-date
 	logic_mux_interrupt_ = false;
 	logic_mux_thread_ = std::thread(&DecodeSignal::logic_mux_proc, this);
@@ -626,6 +613,37 @@ void DecodeSignal::logic_mux_proc()
 	decode_input_cond_.notify_one();
 }
 
+void DecodeSignal::query_input_metadata()
+{
+	// Update the samplerate and start time because we cannot start
+	// the libsrd session without the current samplerate
+
+	// TODO Currently we assume all channels have the same sample rate
+	// and start time
+	bool samplerate_valid = false;
+
+	auto any_channel = find_if(channels_.begin(), channels_.end(),
+		[](data::DecodeChannel ch) { return ch.assigned_signal; });
+
+	shared_ptr<Logic> logic_data =
+		any_channel->assigned_signal->logic_data();
+
+	do {
+		if (!logic_data->logic_segments().empty()) {
+			shared_ptr<LogicSegment> first_segment =
+				any_channel->assigned_signal->logic_data()->logic_segments().front();
+			start_time_ = first_segment->start_time();
+			samplerate_ = first_segment->samplerate();
+			if (samplerate_ > 0)
+				samplerate_valid = true;
+		}
+
+		// Wait until input data is available or an interrupt was requested
+		unique_lock<mutex> input_wait_lock(input_mutex_);
+		decode_input_cond_.wait(input_wait_lock);
+	} while (!samplerate_valid && !decode_interrupt_);
+}
+
 void DecodeSignal::decode_data(
 	const int64_t abs_start_samplenum, const int64_t sample_count)
 {
@@ -647,6 +665,7 @@ void DecodeSignal::decode_data(
 			delete[] chunk;
 			break;
 		}
+
 		delete[] chunk;
 
 		{
@@ -658,6 +677,11 @@ void DecodeSignal::decode_data(
 
 void DecodeSignal::decode_proc()
 {
+	query_input_metadata();
+
+	if (decode_interrupt_)
+		return;
+
 	start_srd_session();
 
 	uint64_t sample_count;
@@ -683,7 +707,7 @@ void DecodeSignal::decode_proc()
 			// Make sure all annotations are known to the frontend
 			new_annotations();
 
-			// Wait for new input data or an interrupt request
+			// Wait for new input data or an interrupt was requested
 			unique_lock<mutex> input_wait_lock(input_mutex_);
 			decode_input_cond_.wait(input_wait_lock);
 		}
@@ -692,37 +716,38 @@ void DecodeSignal::decode_proc()
 
 void DecodeSignal::start_srd_session()
 {
-	if (!srd_session_) {
-		// Create the session
-		srd_session_new(&srd_session_);
-		assert(srd_session_);
+	if (srd_session_)
+		stop_srd_session();
 
-		// Create the decoders
-		srd_decoder_inst *prev_di = nullptr;
-		for (const shared_ptr<decode::Decoder> &dec : stack_) {
-			srd_decoder_inst *const di = dec->create_decoder_inst(srd_session_);
+	// Create the session
+	srd_session_new(&srd_session_);
+	assert(srd_session_);
 
-			if (!di) {
-				error_message_ = tr("Failed to create decoder instance");
-				srd_session_destroy(srd_session_);
-				return;
-			}
-
-			if (prev_di)
-				srd_inst_stack(srd_session_, prev_di, di);
+	// Create the decoders
+	srd_decoder_inst *prev_di = nullptr;
+	for (const shared_ptr<decode::Decoder> &dec : stack_) {
+		srd_decoder_inst *const di = dec->create_decoder_inst(srd_session_);
 
-			prev_di = di;
+		if (!di) {
+			error_message_ = tr("Failed to create decoder instance");
+			srd_session_destroy(srd_session_);
+			return;
 		}
 
-		// Start the session
-		srd_session_metadata_set(srd_session_, SRD_CONF_SAMPLERATE,
-			g_variant_new_uint64(samplerate_));
-
-		srd_pd_output_callback_add(srd_session_, SRD_OUTPUT_ANN,
-			DecodeSignal::annotation_callback, this);
+		if (prev_di)
+			srd_inst_stack(srd_session_, prev_di, di);
 
-		srd_session_start(srd_session_);
+		prev_di = di;
 	}
+
+	// Start the session
+	srd_session_metadata_set(srd_session_, SRD_CONF_SAMPLERATE,
+		g_variant_new_uint64(samplerate_));
+
+	srd_pd_output_callback_add(srd_session_, SRD_OUTPUT_ANN,
+		DecodeSignal::annotation_callback, this);
+
+	srd_session_start(srd_session_);
 }
 
 void DecodeSignal::stop_srd_session()
diff --git a/pv/data/decodesignal.hpp b/pv/data/decodesignal.hpp
index 2d4d4e0c..57887f1e 100644
--- a/pv/data/decodesignal.hpp
+++ b/pv/data/decodesignal.hpp
@@ -145,6 +145,8 @@ private:
 
 	void logic_mux_proc();
 
+	void query_input_metadata();
+
 	void decode_data(const int64_t abs_start_samplenum, const int64_t sample_count);
 
 	void decode_proc();